Nothing inherently wrong with their kits, they just are not exactly like stock. For instance, they are designed to mount up to cars without the sway bar tabls on the lower control arm. To accomplish this they provide an angle bracket that bolts to the lower shock mount. Some people really despise this arrangement, but it is cheap, easy, and effective. Their B body kits use a different mounting bracket arrangement than stock. Again, it is not stock and some dislike it as a result, but it still works.
I've used several of thier kits for different body styles without complaint.